portage-ng / portage / dev-ml / dune / 3.20.2
emerge -vp

These are the packages that would be merged, in order:

Calculating dependencies ... done!
Dependency resolution took 0.98 s (backtrack: 0/20).

[ebuild  N     ] dev-lang/ocaml-5.5.1:0/5.5.1::gentoo  USE="ocamlopt -emacs -flambda -latex -test -xemacs" 6457 KiB
[ebuild  N     ] dev-ml/dune-3.20.2:0/3.20.2::gentoo  USE="-emacs" 2981 KiB

Total: 2 packages (2 new), Size of downloads: 9437 KiB

Wall time
1.949 s vs. 0.012 s for portage-ng